Method of alkylating isoparaffins with 2-olefins



March 28, 195.0 M. P. MATuszAK 2,502,015

METHOD 0F ALKYLATING ISOPARAFFINS WITH Z-OLEFINS Filed Dec. 4, 1942ATTORNEY.

Psrenred- Mn. ze, 195o ALKYLATING ISOPARAFFINS WITH 2-0LEFIN HETHDD FMunn r. Mums, Bartlesville, ous., minor to Phillips Petroleum Company, acorporation ol Delaware Application December 4, 1942, Serial No. 467,873

l 3 Claims.

This invention relates to the production of motor fuels, andmore'particularly to a process in which 2-o1ens are catalytlcallyreacted with low-boilingl isoparalns to produce motor-fuel parafins.

In my copending application Serial No. 441,705, filed May 4, 1942, nowU. S. Patent No. 2,403,671, there is disclosed a process whereby olenshav ing at least four carbon atoms in an open chain are isomerized, oneto another, by contact with an isomerization catalyst. One specicembodiment of the process of the present application involveslsomerization of secondary l-olens to 2-olens, wherein any suitableisomerization catalyst may be used, and utilization of the resulting2-o1ens for catalytic alkylation of low-boiling4 isoparaflins, wherebymotor-fuel parafns superior in quality to those obtainable by similaralkylation with the original l-olens are produced.

An object of this invention is to provide an lmproved process for theproduction of high octane parans suitable forv use as motor` fuel fromlow boiling secondary olens and isoparans of four to five carbon atoms.

Another object of vthis invention is to provide such a -process in which1'olefins are converted to 2-olei'lns prior to alkylation ofisoparailins to produce high octane parafiins suitable for motor fuel.

A specific object of the invention is to produce superior motor-fuelparafns from isobutane and secondary butenes.

Another specific object is to produce superior motor-fuel paraflins fromisobutane and secondary pentenes.

Another specific object is to produce superior motor-fue1 parains fromisopentane and secondary butenes.

Other and similar objects and advantages of this invention will beapparent from the following description, the accompanying drawing and/orthe appended claims. By secondary olens is meant non-tertiary baseoleilns, for example, butene-l, butene-2, pentene-l, pentene-2, 3-methylbutene-l, etc.

One specific embodiment of the present invention comprises isomerizationof at least one secondary 1-olen having at least four carbon atoms in anopen chain, such as butene-l, pentene-l, 3-methyl butene-l, or the like,into the corresponding 2-olefin, such as butene-Z, pentene-Z, 2-'methy1butene-2, or the like, and catalytically alkylating a low-boilingisoparafn,

(CL 26o-4583.4)

resulting 2olen, preferably in the presence of a catalyst comprisingprincipally hydrogen fluo-- ride, whereby are produced parafns'superiorin quality for present-day motor-fuel purposes to those obtainable byalkylation of the isoparailin with the original l-olen.

Understanding of some aspects oi the invention may be facilitated by theaccompanying drawing, which is a flow-diagram illustrating therelationship of various steps in a specilc embodiment of the invention.

`With reference to the drawing, the lvoleiln may enter lsomerizationmeans III through inlet Il controlled by valve I2. In isomerizationmeans l0, it is subjected to the isomerization action of anisomerization catalyst under lsomerization conditions, whereby it isconverted at least partly into the corresponding 2-olen. Theisomerization catalyst is preferably a solid granular material of thetype of magnesia, alumina, bauxite, beryllia, chromla, and the like; itis further preferably a catalyst comprising black chromium oxide. Thesevarious materials are not complete equivalents of eachother, so that theoptimum isomerization conditions for any particular catalyst may differfrom those for another particular catalyst, but in general a suitablecombination of temperature and contact time may be readily found, as bytrial, in the ranges of to 800 F. and of a fraction of a second to manyminutes. Above its critical temperature, the olefin is in the gaseousstate; but below the critical temperature, it is preferably at leastpartly in the liquid state, as the liquid in contact with the catalysthas a desirable washing action on the catalyst.

In many instances, isomerization means Hl may advantageouslyV comprise afractionaldistillation column packed with a granular isomerizationcatalyst and operated in a temperature range below the criticaltemperature of the olefin, whereby it is ensured that the eilluentapproaches the equilibrium composition for the temperature at the exitend of the catalyst bed. The 1olen is fed into the top of the column,and it becomes partly isomerized to the corresponding 2-olen by contactwith the isomerization-catalyst packing. The resulting mixture, which ispartly in the liquid condition, flows downward through the catalystpacking and eventually reaches the end of the packing as a mixture ofapproximately the equilibrium composition for the temperature at thatpoint. This mixture may be passed to fractionation means 20, as throughconduit 2l consuch as isobutaneand/or isopentane, with the 5 5 trolledby valve 22, and may be separated therein into the two isomerlc olefinsby fractional distillation in the absence of an isomerization catalyst;the unconverted l-olefln may then be returned to isomerization means I0,as through conduit 23 controlled by valve 24, and the 2-olef1n may bepassed to alkylation means 30, as through conduit 25 controlled by valve26. Instead of being so separated in fractionation means 20, the mixturemay be advantageously separated by incorporating in isomerizing means Ia lower section that is packed with a non-isomerizing packing or thathas other fractionating devices performing the function of fractionatingplates, whereby the higher-boiling 2-olefin works its way downward andeventually passes from the column, going to alkylation means 30, asthrough conduit 21 controlled by valve 28, whereas the unconvertedl-olefin passes upwardly to the catalyst-packed upper section of thecolumn.

If the original l-olen is in the form of a mixture with the isomeric2-olefln, this mixture may be fed to isomerization means I0 throughinlet Il, but it is preferably fed to fractionation means 20, as throughinlet I3 controlled by valve I4, or to the corresponding point inisomerization means I0 if this is operated as has just been described.

If desired, the fractionation to separate the 2 olefin from unreacted1olefin may be omitted, and the mixture of isomeric olens may be passeddirectly from the isomerization zone to alkylation means 30 throughconduit 21 and valve 28. However, although this mode of operation iseconomical in that the equipment and labor involved in the fractionationis not used, it does not yield an alkylate of the highest qualityobtainable by the fullest application of the principles of thisinvention.

In the foregoing detailed description of the apparatus, it has beenassumed that the olefin feed stock available comprises the 1oleiin. Ingeneral, the secondary or normal butylenes or amylenes available as feedstocks from refinery operations are a mixture of the 1-olen and the2olefin containing high percentages of the 1- olefin. These mixedolefins are advantageously supplied to the process through the pipe I3as previously described. However, the 2-olens may be available in eithersubstantially pure form or may be predominant in a mixture of otherhydrocarbons substantially inert or non-injurious to the alkylationreaction. These 2-olefins may be supplied to the system through the pipei5 controlled by the valve I6. The 2-o1eflns supplied in this manner maymake up any part or all of the olefin feed to the system. In the laterinstance the fractionator and isomerizer I0 may be dispensed with.

In alkylation means 30, the 2-olefin is added t0 an intimate alkylationmixture comprising a molecular excess of an isoparaiiin, such asisobutane and/or isopentane, which is introduced into the system throughinlet 3| controlled by valve 32, and an alkylation catalyst, which isintroduced into the system through inlet 33 controlled by valve 34.Although in general any known alkylation catalyst, such as sulfuricacid, phosphoric acid, sludges comprising polyvalent metal halides suchas aluminum chloride and aluminum bromide, hydroiiuoric acid, boron:fluoride, and mixtures of hydrofiuoric acid and boron fiuoride, may beused, substantially anhydrous hydrofluoric acid is preferred because ofthe relative ease with which it can be used and re-used and because ofthe superior quality of the alkylate that is produced. Known alkylationconditions are employed in alkylation means 30, such as good agitation,a temperature in the range of about 30 to 250 F., sufficient pressure tomaintain the reaction mixture in the liquid phase, a high molecularexcess of isoparaiiin relative to the olefin, a reaction or contact timein the range of about 1 to 90 minutes, and the like. When hydrofluoricacid is the catalyst, preferred alkylation conditions comprisesagitation of the quality produced by an efiicient turbo-mixer, anover-all feed isoparaflin-to-olefin mol ratio in the range of about 3 to10, a temperature in the range of about 85 to 125 F., and an averageresidence time in the alkylation zone of about 5 to 30 minutes. After asuitable residence time, the alkylation mixture is passed throughconduit 35 controlled by valve 36 into separation means 40, in which itis separated into liquid hydrocarbon and catalyst phases, as by gravityand/or centrifugation.

The relatively light or hydrocarbon phase is passed through conduit 4Icontrolled by valve 42 into removal means 50, wherein it is freed fromresidual entrained and/or dissolved catalyst and from unreacted orunalkylated isoparafiin. When hydrofiuoric acid is used as thealkylation catalyst, removal means 50 is preferably afractional-distillation column whercfrom the residual hydrofluoric acidis distilled together with the unreacted isoparadin and is recycled toalkylation means 30, as by conduit 5I controlled by valve 52. Theacidfree kettle product from this column is passed to fractionationmeans 60, as though valve 53 and conduit 54, for separation into motorfuel, which is withdrawn as a product of the process through outlet 6Icontrolled by valve 62, and into a very small and usually negligiblehigh-boiling oil, which is withdrawn through outlet 63 controlled byvalve 64. If, however, the kettle product from removal means 50 has anobjectionable content of organically combined fluorine, it is firstpreferably passed to purification means 10, as through conduit 65controlled by valve 66, for removal of the organic fluorine, whichseldom exceeds 0.01 per cent by weight, as by contacting with a granularmaterial having some degree of afiinity for organic fiuorine, forexample, metal-impregnated contact materials or, more economically,bauxite at a temperature of about 200 to 500 F.; then it is passed, asthrough conduit 1I controlled by valve 'I2 to fractionation means 60.When the catalyst is other than hydrofiuoric acid, means equivalent infunction to removal means 50, fractionation means 60, and/orpurification means 10 can be readily supplied by those skilled in theart of alkylation of paraflins.

The relatively heavy or catalyst phase from separation means 40 ispassed through conduit 'I3 controlled by valve 'I4 to regeneration means80, wherein this phase is treated to recover the catalyst, which isrecycled to alkylation means 30, as through valve 8| and conduit 5I. Theresidue is withdrawn through outlet 82 controlled by valve 83. When thecatalyst is primarily hydrofluoric acid, regeneration means is suitablya fractionation column, wherefrom the hydrofluoric acid is distilledtogether with a relatively small proportion of unreacted isoparaiilndissolved in the catalyst phase.

As has been already stated, in this embodiment of the invention, a solidgranular isomerization catalyst is preferred for the isomerization stagerepresented by isomerization means I0, especially when thisisomerization means is a column packed at least in part with thecatalyst. Among such preferred catalysts are those comprising s blackchromium oxide. Many modes of preparation oi' these black chromiumoxide-containing catalysts have been shown in various publications, asfor example, in U. S. Patents 1,905,383, 2,098,959, 2,270,887,2,274,988, 2,288,320, 2,294,414, and many others, and need not berepeated in detail. All these methods, yielding catalysts comprisingblack chromium oxide, may be said to be characterized by thenon-spontaneous thermal decomposition of one or more chromiumillustrated by the following examples. but the specific details givenshould not. be construed as being necessarily limitative of theinvention.

compounds, such as: chromicV salts, preferably oxide or chromiumsesquioxide, may also be used whenever such catalysts possess anadequate catalytic power for isomerizing- 1-olens to 2- olens. Stillother granular catalysts possessing adequate isomerizing ability may beused, such as many catalysts that contain no chromium oxide of any kind,for example, magnesia, and par ticularly. calcined brucite, which is anespecially economical magnesia olefin-isomerization cata lyst.

However, in the broad concept of this invention, the isomerizationcatalyst need not be a solid or granular material, butit may be anymaterial that can effect a desired extent of isomerization of l-olens to2olefns. A number of suitable catalysts are known, such as perchloricacid, phosphoric acid, benzene sulfonic acid, and zinc chloride; theseand other catalysts, such as calcium oxide, silica, titania,silica-alumina, and the like, that may be useful in particular instancesare mentioned, for example, in Chapter II of Isomerization of PureHydrocarbons by Egloif, Hulla and Komarewsky (1942) It should beunderstood that, ,except as may be specified in the appended claims, theinvention is not to be limited to any particular isomerization catalyst.The catalyst may be one that causes a minor or incidental isomerizationof normal or secondary olens to isoolens; isomerization of secondaryolens to isoolefins followed by hydrouoric acid alkylation of isobutanewith the resulting isoolefins to obtain motor fuel of high octane ratinghas been disclosed in mycopending application Serial No. 467,411, filedNovember 30, 1942, and now abandoned. t

When the use of a liquid catalyst is desired for the isomerizationstage, it is usually advantageous to use aqueous hydrofiuoric acidcontaining between about 50 and 80 per cent hydrogen fluoride by weight,and preferably about 65 per.

Aqueous sulfuric acid containing aboutcent. 'l0 'to 90 per cent sulfuricacid by weight, preferably about 80 per cent, may be used likewise, buta certain amount of loss occasioned by the oxidizing power of this acidis to be expected. These and other acid-type catalysts have thedisadvantage that they promote polymerization of olens as well asisomerization.

In the broadest concept of this invention, the isomerization catalystmay be omitted, and the isomerization of the l-olen may be carried outnoncatalytically. However, in such case. -the temperature is so high,above about 1100 F., that the isomerization equilibrium is adverselyaffect- Example I In a continuous process similar to that illus-l tratedby the drawing, butene-l is passed at about atmospheric pressure througha bed oi' chromium oxide gel-type granules at about 450 to 700 F. at aspace velocity of about 1000 vapor volumes per catalyst volume per hour,whereby about four-fifths of it is converted to butene-2. The resultingmixture of butylenes is condensed by cooling and compression, andispassed to an alkylator for the hydrofiuoric acid alkylation ofisobutane.A In the alkylator, intimate mixing is obtained with aturbo-mixer; the temperature is about 110 to 120 F.; the volume ratio ofhydrocarbons to'hydrofluoric acid is about 1.5 to 2.0; the over-all molratio of isobutane to butylene is about 9; and the average residencetime of the alkylation mixture is about 8 to 12 minutes. The alkylateproduced under these conditions, when isolated from the acid and fromthe unreacted isobutane and out to an end point of about 390 F., has anASTM octane number of about 91.8, which is increased to about 101.6 by lcc. of lead tetraethyl per gallon.

Under the sameconditions, but without the -preliminary isomerization,the alkylate produced from isobutane and butene-l has an octane numberof only about 88.9, which is increased to about 99.8 by 1 cc. of leadtetraethyl per gallon. The

isomerization of the original butene-l to butene-2 thus cooperates withthe alkylation to produce an alkylate of advantageously considerablyimproved octane rating.,

Example II The process is carried out as in Example I except that theeffluent from the isomerization step is fractionally distilled to removeunconverted butene-l, which is recycled to the isomerization step. Thealkylate produced with the resulting kettle product by alkylatingisobutane under the conditions given in Example I has an octane numberof about 92.5, which is increased to about 102.0 by l cc. leadtetraethyl per gallon. The octane rating is thus substantially increasedby incorporation of the fractionation step into the process.

Example III Butene-l is subjected to the isomerization action ofgranular calcined brucite at about 200 to 280 F. The space velocity isabout 1 to 5 liquid volumes per catalyst volume per hour, and thepressure is sufficient to maintain the hydrocarbon in the liquid phase.When the isomerization eilluent is used directly for hydrofluorc acidalkylation of isobutane under the alkylation conditions given in ExampleI, the resulting aviationrange alkylate'has an ASTM octane number ofabout 92.0; when the isomerization eiiluent is preliminarilyfractionated to free the butene-2 from unreacted butene-l before it isused for alkylation of isobutane vunder these conditions, the alkylatehas an ASTM octane number of about 92.5.

Example IV Two exploratory batch-type .runs were made for the hydrouoricacid alkylation of isobutane under substantially similar conditions; onewas rer. The most pertinent data may be summamade with butene-l and theother with butano-2. rized as follows: The runs were made in an 18-litersteel reactor provided with a mechanically driven stirrer. The 016mlPentened Pemene-2 most pertinent data may be summarized as fol- 5 lows:Hydrocarbons/HF (vol.) 3. s2 3. 31 sobutane/oleimolh.- 9 9.85 10. 93

m 016011 Buteiiei Bowie-2 1226533 it, min. (avg.) 7 112 mi2Aviation-range alkylate: lo Cut point, F 320 347 HydrocarbonSHF (v01.)4. 08 4- 01 Yield, v01. per cent- 56. 4 01. 0 Isobutane/oleiln (mol) 12.4 15. 1 Octane No. (ASTM Temperature, F.... 99-113 99 0 cc. TEL-- 83. 889. 2 Reaction time, min. 14. 5 25 1 cc. TEL.. 93.0 100. 4Aviation-range alkylate:

Gilt point 52 91363 r gevlgrl-pg191ij II 8012 027 x5 'Ifhese datademonstrate that Dentelle-2 is Silj perior to pentene-l for thehydrouoric acio These data demonstrate that butene-2 is sualkylatlon oflsobutane' perior to butene-l for the hydrouoric acid alkyl- Example VHatm of lsobutane Two exploratory batch-type runs were made Example V forthe hydroiiuoric acid alkylation of isopentane A run was made for thehydrouorc acid anwb under substantially similar conditions; one was madewith butene-l and the other with butene-2. ation of isobutane in a smallcontinuous pilot Th r ns re m d in 18 nt t l t w plant comprising aturbo-mixer reactor arid a r evdld Wfh a rnarl d'1 er 55e reafm;separator whererom the acid phase was recycled En? t erg/1e 'nc I; cab yt ven s llrer 1r to the reactor by gravity. One portion only of 1 Wss pn n a a' ay e Summarize as o substantially anhydrous hydroiluoric acidwas 0 used, without replacement of consumed acid. l Eight batches ofproduct were made; the first 0101i Buteu-l Bumm-2 three were obtainedfrom butene-2 as the olen, 30 the next three from butene-l, the next tolast HYdr0Cafb01S/HF(v1- 1 1 Iso ntane olefin m01 8.31 .5 with butene-2,and the last with butene-l. Be- Teeperatu/re, 66-100 68i02 Reactiontime, min. (avg.) 25 2' cause of experimental difculties.. the volumeAviatiomange alkylate: 0 ratio of hydrocarbons to hydrofluoric acid mthe cui poing, F 284 203 Yield, vo per cent 80.7 84.3; reactor, asdetermined by examination of sani 0eme No. (ASTM) ples withdrawn fromthe reaction mixture, varied 0 ce, TEL 74.6 16. somewhat during the run.When production of cc- TEL 87-7 8H a particular batch of product wasconcluded, the reactor was stopped, and the hydrocarbon phase These datademonstrate that butene-2 is suin it and in the separator were removed,to avoid 4o perior to butene-l for the hydrofiuoric acid alkylmixing ofdifferent batches. The data may be ation of isopentane. summarized asfollows: Since this invention may be practiced otherwise Batch ofproduct l. 2 3 4 5 6 7 8 Timeinrun, min 0-30 :a0-s2 82-823 321-551551-612 G12-642 642-661 661-614 Butene (-1 or -2),.. 2 i 1 1 1Temperature, F. (Av 113 114 115 116 116 111 116 111 Hydrocarbons/HF(V01. 2.0 1.5 1.1 1.2 1.3 2.8 1.8 4.5 @burma/111116116111101). s. 018.01 8. 01 0. 05V 0.05 0.05 8.01 0.05 ooiimcinme, min. (avg.) 1.5 0.245.6 42.0 11.6 8.1 6.0 8.4 Alkylate yield, wt. per cent of butene.- 175196 213 210 205 207 166 199 Aviation-gasoline fraction:

cuipoim, "F 401 318 810 300 388 381 31s 383 Yield, vol. per cent.---.98.3 96.3 98. 6 98. 5 98. 2 98. 7 98.2 97. 4 Reid vapor pressure, 1b.5.85 3.30 3.90 3.55 3. 55 1.35 3.50 3.30 Gravity, API 10.6 10.0 10.410.0 60.1 60.2 60.0 50.5 ASTM dist' ation, F.:

02.8 01.1 88.1 80.2 88.1 03.5 88.2 ice'rEL- 101.0 101.6 00.1 101.2 00.1102.5

These data show that under comparable alkylatioii conditions, butene-2is definitely superior to buteiic-l or the hydrouoric acid alkylation ofisobutane.

Example VI than as specifically described or illustrated, and since manyvariations and modications of it 7n will be obvious to those skilled inthe art, this invention should not be restricted otherwise than asspecified in the appended claims.

I claim:

1. In a process of producing motor fuel from Z5 an isoparaifin and amixture of 1- and 2-olens in which the i-oleiin is at least in partisomerized to 2-olen by the action of a liquid isomerization catalystand the isoparafiin is alkyiated with the 2-o1eiin in the presence ofconcentrated hydroiiuoric acid, the improvement which comprises using asthe liquid isomerization catalyst aqueous hydrouoric acid containingbetween 50 and 80 per cent hydrogen fluoride by weight.

2. In a process of producing motor fuel from an isoparafn and a mixtureof 1- and 2-o1ens in which the l-oiefin is at least in part isomerizedto 2-oien by the action of a liquid isomerization catalyst and theisoparaiiin is alkylated with the 2-o1efin in the presence ofconcentrated hydrouoric acid, the improvement of which comprises usingas the liquid isomerization catalyst aqueous hydrofiuoric acidcontaining 65 per cent hydrogen iluoride by weight.

3. The process of claim 1 wherein the said mixture of 1- and 2-o1et1nsis rst subjected to fractionation in a fractionation zone into frac-REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Number Name Date 1,914,674 Runge et al June 20,1933 2,128,971 Snow Sept. 6, 1938 2,227,559 Stevens et al. Jan. 7, 19412,267,730 Grosse et al Dec. 30, 1941 2,327,926 Oakley et al Aug. 24,1943 2,335,704 Smith Nov. 30, 1943

1. IN A PROCESS OF PRODUCING MOTOR FUEL FROM AN ISOPARAFFIN AND AMIXTURE OF 1- AND 2-OLEFINS IN WHICH THE 1-OLEFIN IS AT LEAST IN PARTISOMERIZED TO 2-OLEFIN BY THE ACTION OF A LIQUID ISOMERIZATION CATALYSTAND THE ISOPARAFFIN IS ALKYLATED WITH THE 2-OLEFIN IN THE PRESENCE OFCONCENTRATED HYDROFLUORIC ACID, THE IMPROVEMENT WHICH COM-D HYPRISESUSING AS THE LIQUID ISOMERIZATION CATALYST AQUEOUS HYDROFLUORIC ACIDCONTAINING BETWEEN 50 AND 80 PER CENT HYDROGEN FLUORIDE BY WEIGHT.